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Want to build my own sub... some advice needed. (im a NEWB) (1 Viewer)

TimForman

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Dec 4, 2002
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You've probably reached the point where the speaker is distorting at it's resonance frequency causing a voltage peak. You're correct that the amp protection circuitry is kicking in. You're also correct that it's not designed to be run this way and that a box would help stabilize it.
 

Anthony_I

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well like i said i simply wanted to test the speaker, if its in a box this wont happen will it.
 

Jack Gilvey

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"Testing" the woofer in this fashion tells you absolutely nothing about how it will perform.
Seems ok for a cheap woofer. Weak motor, fairly high Qts. Try it in the recommended box and see what happens.
 

Anthony_I

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I've heard it in its recommended box, and it sounds REALLY good, and by testing i meant only to test if the speaker worked.
and what do you mean "cheap"??

Im not rich, nor do i have tons of money to spend on stuff like this, so i cant go out and spend $400 on a speaker. all of the stuff i will be getting will come over time, not al at once.
 

TimForman

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what do you mean "cheap"??
I'll try to put it in perspective. Jack's very fond of the Adire DPL12 which, around here, sells for $150 USD. The Phoenix Gold driver you're using sells for $68 USD, so many of us "snobs" consider it a cheap driver. Looking at the specs it's very competitive for the price. Try not to take it personally. By the time you get through this I think you'll end up with a respectable sub. I would like to add that I respect your attitude in that you're willing to go through the steps (math and all) that many are not. Welcome to the club.
 

Anthony_I

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of course i am willing to go through the math and all... not only do i want to know how to make a kick ass sound system, i want to understand why/how it is working. but what steps etc are you talking about that others are not willing to do?

and ive seen the octane r12d listed fo rmore than $68 USD.

but either way i have the speaker and now im pretty much waiting until my next pay so i can this other guy his money for the amp i "bought".
 

Brian Bunge

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The smaller, .9ft^3 box will sound really "impressive" but it will have a peak in the response and won't extend as low as the larger box. IIRC, the 3ft^3 box gives a Qtc=.707 which makes a good combination music/HT sub.
 

Anthony_I

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then i shall find/build a box that is 3 Cu Ft.

mind you that 0.9 Cu. Ft. box includes the speaker displacement. so should the 3 Cu Ft box be somthing like 2.9 or something?

there arent enough specs included for me to figure out how much space the speaker displaces.
 

TimForman

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what steps etc are you talking about that others are not willing to do?
I've seen postings on other forums where the belief is promoted that it's not necessary to calculate volume, port size, etc.. and all that's needed is to throw a driver in a box with and amp and away you go. :thumbsdown:
 

Anthony_I

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Well thats quite mad sir, quite mad indeed.

one of the first things i started learning about was speakers/boxes and how to build them and what speaker would sound good with my system and how to make it sound good/better.

one one of the first things i learned about that, was that the volume of the box is detrimental(sp) to the speakers functions/sound.

it affects many things such as cone displacement, it acts as "back pressure" for the speaker to keep it from moving too far/too fast.

one thing that i just thought about though is that a 3Cu Ft box may not work well with this speaker, there may not be enough "back pressure" to keep the speaker as sturdy as it needs to be so as not to bottom out or cause problems like it does outside of the box.

although i may go slightly larger, not quite that big though.
 

Anthony_I

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Sep 9, 2003
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also, how exactly does phase response change the way it sounds?

what is phase??? is that like looking at a sine wave from the end and roating it like a clock ( | - / | )
if that description or diagram make any sense.
 

Cees Alons

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Cees Alons
Anthony,

The phase response determines if the wave that's coming out of the speaker is "delayed" a bit or not. That wouldn't be too bad, except that it's different at different frequencies and therefore can diminish the exactness of the whole sound.

Around the resonance frequencies of a bass-system, the phase-response tends to shift. So a bass box is "tighter" and more "precise" if that shift is less (e.g. when the resonance frequency is low - almost below any real audio frequency, or if it has a flatter resonance peak).

Cees
 

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